diff --git a/dask_cuda/local_cuda_cluster.py b/dask_cuda/local_cuda_cluster.py
index 82f59346..d0ea9274 100644
--- a/dask_cuda/local_cuda_cluster.py
+++ b/dask_cuda/local_cuda_cluster.py
@@ -332,16 +332,17 @@ def __init__(
             enable_rdmacm=enable_rdmacm,
         )
 
-        if worker_class is not None and log_spilling is True:
-            raise ValueError(
-                "Cannot enable `log_spilling` when `worker_class` is specified. If "
-                "logging is needed, ensure `worker_class` is a subclass of "
-                "`distributed.local_cuda_cluster.LoggedNanny` or a subclass of "
-                "`distributed.local_cuda_cluster.LoggedWorker`, and specify "
-                "`log_spilling=False`."
-            )
-        if not isinstance(worker_class, Nanny):
-            worker_class = partial(Nanny, worker_class=worker_class)
+        if worker_class is not None:
+            if log_spilling is True:
+                raise ValueError(
+                    "Cannot enable `log_spilling` when `worker_class` is specified. If "
+                    "logging is needed, ensure `worker_class` is a subclass of "
+                    "`distributed.local_cuda_cluster.LoggedNanny` or a subclass of "
+                    "`distributed.local_cuda_cluster.LoggedWorker`, and specify "
+                    "`log_spilling=False`."
+                )
+            if not issubclass(worker_class, Nanny):
+                worker_class = partial(Nanny, worker_class=worker_class)
 
         self.pre_import = pre_import